Pre emergent herbicides will keep weed seeds from germinating but won't control existing weeds. The best time to apply pre emergence products is in the early spring, before weeds pop up. You can use a weed control product now and feed your lawn in November with a winterizer type fertilizer. Many products are available in liquid and granular formulations. Included are Ortho Weed-B-Gon Weed Killer For Lawns, Southern Ag Lawn Weed Killer with Trimec, Ace Spot Weed Killer, Ortho Basic Solutions Lawn Weed Killer, and Bayer Advanced Southern Weed Killer for Lawns. One reason for the popularity of these products is that most of these can be applied to all of the commonly grown turfgrasses in the south including Bermuda grass lawns.